Analysis of Stability of Pile Foundation with Higher Pile-column Bridge Piers

Based on difference between pile foundation with higher pile-column bridge piers and normal pile foundation and taken interaction of pile, pier and soil into account, a pile-column calculation model was founded. On the assumption that the lateral friction distributed uniformly with soil layer and horizontal foundation coefficient of soil increased linearly by depth, the total potential energy of the pile-soil system was gained by using energy method with consideration of material properties and geometry properties of pile and column in pile foundation with higher pile-column bridge piers. And buckling critical load and stability calculation length were derived by theory of conservation of potential energy. Numeric computation result shows that (1) stability of pile foundation with higher pile-column bridge piers can be enhanced by improving the character of soil, while the stiffness ratio of pile and column is larger and embedding ratio of pile is less, the effect of stability is limit; (2) the dimensionless stability calculation length increases with increases of embedding length of pile; (3) maybe there exists an optimal stiffness ratio of pile and column in pile foundation with higher pile-column bridge piers for the column-pile-soil system works in phase. The calculation result agrees well with the numerical result by finite element program.